The invention relates to fabricating composite-material turbomachine blades having a bottom and/or top platform incorporated therein.
The intended field is that of gas turbine blades for aeroengines or for industrial turbines.
Proposals have already been made to make composite material blades for turbomachines. By way of example, reference may be made to document EP 1 526 285, which describes fabricating a fan blade by making a fiber preform by three-dimensional weaving and by densifying the preform with a matrix.
Furthermore, in order to make structural parts of a turbomachine that are exposed to high temperatures in service, proposals have already been made to use thermostructural composite materials, and in particular ceramic matrix composite (CMC) materials. Compared with metal alloys, such materials can present improved high temperature performance and lower weight, while also having the mechanical properties needed for constituting structural parts. In particular for aeroengine gas turbines, it is desired to reduce weight and to reduce polluting emissions by increasing temperature.
Document EP 1 801 354 describes separately forming a preform for a blade airfoil and root and a preform for a platform by draping plies that are pre-impregnated with a resin and by partially polymerizing the resin. The platform preform has cheeks that are placed against opposite faces of the blade airfoil-and-root preform, over its root. After continuing polymerization, impregnation by a binder (silicon) is carried out in order to bond together the cheeks of the platform and the facing faces of the blade root.
The rigidification provided by the pre-polymerization restricts the complexity that it is possible to obtain in the shape of the airfoil profile.